Cook calls iOS "the biggest release of iOS since the introduction of the App Store" (which was in 2008). "Together our devices provide an integrated and continuous experience across all of them. And developers can create powerful apps more easily than they've ever been able to.

"Apple engineers platforms, devices and services together. We do this so we can create a seamless experience for our users that is unparalleled in the industry. This is something only Apple can do."

Federighi says "what if you had Objective-C without the C?" Apple introduces a new programming language, Swift. It's a modern programming language - for which the developers are going wild (if you know what a "tuple" is, then you'd be excited. If not - it's an ordered list of elements. Programmers love them.) Swift benchmarks show it's very, very fast, Federighi says.

iOS 8 will introduce HomeKit to let you manage home automation

"We've come up with HomeKit to allow secure pairing so that only your iPhone can unlock your garage door. With Siri integration you can say something like 'Get ready for bed' and be sure the garage door is closed, the lights are dimmed, the doors are locked."

Looking back at Tim Cook's "130m new users on iOS in the past 12 months" - in the four quarters to the end of March 2014, Apple sold 71m iPads and 160m iPhones, or 231m iOS devices (give or take a few million more iPod Touches).

That means that 130m of the 231m iOS devices went to new users - 56%, which feels like a remarkably high figure.

"Extensibility" - apps being able to offer services to other apps. This is like Android's "intents" - also called XPC (cross-program communication).

"Extensions live inside an application's sandbox, but apps can reach through the OS to request. Pinterest can offer a share sheet to Safari. Bing can offer translation inside Safari. Photo filters inside of photos. Third party apps can define widgets with notifications."

Developers have been looking forward to this for a long time; iOS has lagged Android (which has had "intents" from its inception) and Windows Phone (which gained it in Windows Phone 8).

Federighi demonstrates an app providing a watercolour effect to a photo in the photo library.

"Widgets" appear in the Notification Centre - not on the Home screen. They are interactive and updated and you can interact with them directly - Federighi demonstrates an eBay widget that he can use to bid directly from the Notification Centre.

Or Bing translation - which is offered directly. (It's noticeable that Apple hasn't gone for Google translation; Google has had very little mention through the keynote.)

"There is a lot more - what iOS 8 provides for developers to create apps you couldn't create before," says Cook. The App Store now has 1.2m apps with an "unbelievably vibrant" market. 300 million people visit the store every week. 75bn apps downloaded.

"We want to make the App Store even better." New features on the store - an 'Explore' tab, with trending searches, faster search, related searches, discounted bundles.

App previews - short videos of apps. (Britain's Monument Valley by UsTwo shows on the screen.)

Testflight - developers can ask users to beta test their app and get feedback.

iOS 8 adds Shazam song recognition - Siri will recognise a song around you. Streaming voice recognition, so that it will show what it thinks you've said, and 22 new languages that it understands. Vector-based maps in China. A lot of improved elements for China - one of Apple's most important markets.

"Family sharing" will let you create a "family" photo stream, calendar, Find My Friends ("with permission") and find your devices. Also sharing music, books, apps, films. "With Family Sharing you can get at your purchases but also the purchases of members of your family. You just click right through and download. For up to six family members." All on a single credit card - but parents get an alert when a child wants to buy something in a story.

In effect, it's Apple's response to Microsoft's "Kids Corner" (which ropes off part of the phone and its apps.)

• Photos and iCloud: "every photo you take on all your devices": "We're not only preserving - your device has access to more photos in the cloud than you can store on your device." Adds search for locations, time and album titles.

"And now something that we all care a lot about - health," says Federighi. "Developers have created a lot of apps for monitoring your health. But up to now the information gathered by those applications lives in silos. But now you can with HealthKit. A single place where applications can gather the data. And there's an app - Health.

"We carefully protect your privacy - you can decide what you want to share between apps." Working with the Mayo clinic so that if a patent takes a blood pressure reading, and it's out of normal bounds, it will feed back to the clinic automatically.

Apple iOS keyboard gets "Quicktype". In iOS 8 you get predictive typing suggestions (a form of which has been in Android for a while) - but given the question in a message "Do you want to go for dinner or a movie?" You'll be offered different choices - "dinner", "movie", "not sure".

Spotlight suggestions: able to pull instant information from the web, from Wikipedia, iTunes to movie times

QuickType - supports predictive typing suggestions very much like Android has had for a while, including learning to the way that the user types. All done on-device ensuring none of the user typing leaves the device

Overall satisfaction for iOS 7 is 97%, according to a ChangeWave survey, and 89% now using the latest version, says Cook. "This is in stark contrast to Android, where "when you look at their latest release less than 1 in 10 customers - 9% - are on their latest software. And over a third of their customers are running a version of Android from four years ago." That means they are not getting great new features or security updates that they may need to stay safe, says Cook. "And this is particularly important for Android which dominates the mobile malware market."

iOS has brought more than 130 million customers in the past 12 months - it was their first Apple device. Many were switchers from Android, says Cook: "they had bought an Android phone and they sought a better experience and decided to check out iPhone and iOS. In fact nearly half of our customers in China in the past six months switched from Android to iPhone."

Apple adds SMS reception (not just its own iMessage) and phone calls on the desktop – which you can accept and receive (and reply to, or take the calls) – "even if your phone is across the house on a charger," says Federighi. You can dial your phone from your OS X device - essentially bringing the OS X user base into the iOS user base.

"We're going to take proximity-awareness and make it easier. Your Mac will see your phone and it will automatically set up a hotspot without you having to type a password. Even if your phone is across the room sitting in a handbag," says Federighi.

Craig Federighi announces "iCloud Drive" - showing the documents in the cloud-based iCloud, shows up like folders. It's very Dropbox-like. It's the first time that iCloud has had a filesystem-based appearance.

Mac OSX, the desktop software, is getting a dramatic overhaul in appearance - its first big change since the introduction of the new software in 2001. It's a flatter appearance, echoing the IOS 7 change - but retaining shadows for the idea of depth.

Apple’s share of the US smartphone users will rise to 40.5% up from 40% in 2013 and 36.5% in 2012, according to data from eMarketer. By comparison Google’s Android will claim 50% of smartphone users in 2014, up from 49.5% in 2013.

In the UK, Apple’s numbers are slightly lower. Apple is expected to claim 30.5% of smartphone users this year, up from 29% in 2013, while Android smartphone users will account for 53% of the market in 2014 compared to 54.5% in 2013, according to eMarketer.

The audience - some of whom have been queueing since 5.30am - is expecting an announcement around the smart home, the "Healthbook" app to store health data, and new versions of the desktop and mobile software.

The latter tends to matter more because it will be pushed out to so many more people and so quickly: there are more people using iOS 7 than any single point version of Android. But don't expect new iPhones or iPads - it's the wrong time of year.

Apple's annual Worldwide Developer Conference kicks off at 6pm UK time. Charles Arthur is there, and will bring you all the latest announcements direct from San Francisco. No frills - we'll pick out all the most essential details you need to know.